Magnetic tunneling junction device and memory device including the same

ABSTRACT

Provided are a magnetic tunneling junction device having a relatively high tunneling magnetoresistance (TMR) ratio; and a memory device including the magnetic tunneling junction device. The magnetic tunneling junction device includes: a pinned layer having a first surface and a second surface opposite the first surface; a seed layer disposed in contact with the first surface of the pinned layer; a free layer disposed to face the second surface of the pinned layer; and a tunnel barrier layer disposed between the pinned layer and the free layer, wherein the seed layer includes at least one amorphous material selected from CoFeX and CoFeXTa, and the X includes at least one element selected from niobium (Nb), molybdenum (Mo), tungsten (W), chromium (Cr), zirconium (Zr), and hafnium (Hf). The seed layer may not include boron.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application No. 10-2022-0002960, filed on Jan. 7, 2022,and Korean Patent Application No. 10-2022-0073058, filed on Jun. 15,2022 in the Korean Intellectual Property Office, the disclosure of whichis incorporated by reference herein in its entirety.

BACKGROUND

Example embodiments relate to magnetic tunneling junction devices andmemory devices including the magnetic tunneling junction devices and,more particularly, to magnetic tunneling junction devices having a hightunneling magnetoresistance (TMR) ratio, and/or memory devices includingthe magnetic tunneling junction devices.

A magnetic memory device such as magnetic random-access memory (MRAM)stores data by using a change in the resistance of a magnetic tunnelingjunction device. The resistance of a magnetic tunneling junction devicevaries with the magnetization direction of a free layer. For example,when the magnetization direction of the free layer is the same as themagnetization direction of a pinned layer, e.g. are parallel with eachother, the magnetic tunneling junction device may have low resistance,and when the magnetization directions are opposite to each other, e.g.are antiparallel with each other, the magnetic tunneling junction devicemay have high resistance. When this characteristic is used in a memorydevice, for example, a magnetic tunneling junction device having lowresistance may correspond to data such as logical ‘0’ and a magnetictunneling junction device having high resistance may correspond to datasuch as logical ‘1’. In order to improve the performance of such amagnetic tunneling junction device, a tunneling magnetoresistance (TMR)ratio having a high value is beneficial.

SUMMARY

Provided are magnetic tunneling junction devices having a relativelyhigh tunneling magnetoresistance (TMR) ratio and/or memory devicesincluding the magnetic tunneling junction devices.

Alternatively or additionally, provided are magnetic tunneling junctiondevices having a relatively high exchange field (Hex) and memory devicesincluding the magnetic tunneling junction devices.

Alternatively or additionally, provided are magnetic tunneling junctiondevices that may be manufactured by performing heat treatment at atemperature equal to or greater than 300° C. and/or memory devicesincluding the magnetic tunneling junction devices.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the various example embodiments.

According to some example embodiments, a magnetic tunneling junctiondevice may include a pinned layer having a first surface and a secondsurface opposite the first surface; a seed layer in contact with thefirst surface of the pinned layer; a free layer facing the secondsurface of the pinned layer; and a tunnel barrier layer between thepinned layer and the free layer. The seed layer includes at least oneamorphous material selected from CoFeX and CoFeXTa, where the X includesat least one element selected from niobium (Nb), molybdenum (Mo),tungsten (W), chromium (Cr), zirconium (Zr), and hafnium (Hf).

A proportion of the X in the seed layer may be about 5 at % to about 50at %.

A thickness of the seed layer may be or be about 5 Å (0.5 nm) to or toabout 15 Å (1.5 nm).

The seed layer may be a single layer including CoFeXTa.

The seed layer may include a first seed layer facing the first surfaceof the pinned layer and a second seed layer between the pinned layer andthe first seed layer to contact the first surface of the pinned layer.

The first seed layer may include CoFeX and the second seed layer mayinclude tantalum (Ta).

A thickness of the second seed layer may be less than a thickness of thefirst seed layer.

The magnetic tunneling junction device may further include ananti-crystallized layer between the pinned layer and the tunnel barrierlayer; and a polarization enhancing layer between the anti-crystallizedlayer and the tunnel barrier layer.

The seed layer and the anti-crystallized layer may be maintained in anamorphous state at a temperature of about 300° C. to about 500° C.

The anti-crystallized layer may include at least one of YCo, YFe, YCoFe,YCoB, YFeB or YCoFeB, and the Y may include at least one elementselected from tungsten (W), rhenium (Re), molybdenum (Mo), and tantalum(Ta).

The anti-crystallized layer may include YFeB, a proportion of FeB in theanti-crystallized layer may be about 20 at % to about 60 at %, and aproportion of boron (B) in the FeB may be about 10 at % to about 30 at%.

A thickness of the anti-crystallized layer may be about 1.5 Å to about10 Å.

The polarization enhancing layer may include CoFeB.

The polarization enhancing layer may include a first polarizationenhancing layer in contact with the anti-crystallized layer, and asecond polarization enhancing layer between the first polarizationenhancing layer and the tunnel barrier layer.

Each of the first polarization enhancing layer and the secondpolarization enhancing layer may include CoFeB, and a proportion ofboron (B) in the second polarization enhancing layer may be less than aproportion of boron (B) in the first polarization enhancing layer.

The proportion of boron (B) in the first polarization enhancing layermay be about 25 at % to about 35 at %, and the proportion of boron (B)in the second polarization enhancing layer may be about 15 at % to about25 at %.

A thickness of the second polarization enhancing layer may be less thana thickness of the first polarization enhancing layer.

The thickness of the first polarization enhancing layer may be or beabout 5 Å to or to about 7 Å, and the thickness of the secondpolarization enhancing layer may be or be about 1 Å to or to about 3 Å.

The pinned layer may include a first ferromagnetic layer in contact withthe seed layer, a second ferromagnetic layer in contact with theanti-crystallized layer, and a synthetic antiferromagnet (SAF) couplinglayer between the first ferromagnetic layer and the second ferromagneticlayer, and a magnetization direction of the first ferromagnetic layerand a magnetization direction of the second ferromagnetic layer may beopposite to each other.

The magnetic tunneling junction device may further include an oxidelayer on the free layer.

According to an some example embodiments, a method of manufacturing amagnetic tunnel junction device includes forming a seed layer on anelectrode; forming a pinned layer on the seed layer; forming ananti-crystallized layer on the pinned layer; performing a heat treatmentfor crystallizing the pinned layer; forming a polarization enhancinglayer on the anti-crystallized layer; forming a tunnel barrier layer onthe polarization enhancing layer; and forming a free layer on the tunnelbarrier layer. The seed layer comprises at least one amorphous materialselected from CoFeX and CoFeXTa, and the X comprises at least oneelement selected from niobium (Nb), molybdenum (Mo), tungsten (W),chromium (Cr), zirconium (Zr), and hafnium (Hf).

The heat treatment may be performed at a temperature of 300° C. to 500°C.

According to some example embodiments, a memory device includes aplurality of magnetic tunneling junction device and a plurality ofswitching devices, each of the plurality of switching devices beingconnected to a respective one of the plurality of magnetic tunnelingjunction devices, wherein the one of the plurality of magnetic tunnelingjunction devices includes a pinned layer having a first surface and asecond surface opposite the first surface; a seed layer in contact withthe first surface of the pinned layer; a free layer disposed to face thesecond surface of the pinned layer; and a tunnel barrier layer disposedbetween the pinned layer and the free layer. The seed layer includes atleast one amorphous material selected from CoFeX and CoFeXTa, and the Xincludes at least one element selected from niobium (Nb), molybdenum(Mo), tungsten (W), chromium (Cr), zirconium (Zr), and hafnium (Hf).

According to some example embodiments, a magnetic junction tunnelingdevice may include a pinned layer having a first surface and a secondsurface opposite the first surface; a seed layer contacting the firstsurface of the pinned layer; and a free layer facing the second surfaceof the pinned layer. The seed layer comprises at least one amorphousmaterial selected from CoFeX and CoFeXTa, and the X comprises at leastone element selected from niobium (Nb), molybdenum (Mo), tungsten (W),chromium (Cr), zirconium (Zr), and hafnium (Hf).

The magnetic junction tunneling device may include an electrodecontacting a surface of the seed layer.

A memory device may include the magnetic tunneling junction device; anda switching device including a first source/drain terminal, the firstsource/drain terminal connected to the electrode of the magnetictunneling junction device.

The memory device may include a selection line; and a word lineextending parallel with the selection line. The switching device mayfurther include a second source/drain terminal connected to theselection line and a gate connected to the word line.

The memory device may include a bit line, wherein the free layer of themagnetic tunneling junction device is connected to the bit line.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and/or advantages of certainexample embodiments will be more apparent from the following descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view illustrating a schematic structure of amagnetic tunneling junction device according to some exampleembodiments;

FIG. 2 is a cross-sectional view illustrating a schematic structure of amagnetic tunneling junction device according to some exampleembodiments;

FIG. 3 is a cross-sectional view illustrating a schematic structure of amagnetic tunneling junction device according to some exampleembodiments;

FIG. 4 is a cross-sectional view illustrating a schematic structure of amagnetic tunneling junction device according to some exampleembodiments;

FIG. 5 is a cross-sectional view illustrating a schematic structure of amagnetic tunneling junction device according to some exampleembodiments;

FIG. 6 is a cross-sectional view illustrating part of a process ofmanufacturing a magnetic tunneling junction device;

FIG. 7 is a graph illustrating results of X-ray diffraction (XRD)analysis of a seed layer;

FIG. 8 is a graph illustrating results of XRD analysis of ananti-crystalized layer;

FIG. 9 is a graph illustrating a resistance-area product and a tunnelingmagnetoresistance (TMR) ratio of magnetic tunneling junction devicesaccording to various manufacturing process conditions;

FIG. 10 is a graph illustrating a Kerr rotation angle with respect to anexternal magnetic field in a magnetic tunneling junction deviceaccording to some example embodiments compared with a comparativeexample;

FIG. 11 is a cross-sectional view illustrating a schematic structure ofa magnetic tunneling junction device according to some exampleembodiments;

FIG. 12 schematically illustrates one memory cell including a magnetictunneling junction device according to some example embodiments;

FIG. 13 is a circuit diagram schematically illustrating a configurationof a memory device including a plurality of memory cells shown in FIG.12 ; and

FIG. 14 is a block diagram of an electronic apparatus according to someexample embodiments.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments, examples ofwhich are illustrated in the accompanying drawings, wherein likereference numerals refer to like elements throughout. In this regard,example embodiments may have different forms and should not be construedas being limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items. Expressionssuch as “at least one of,” when preceding a list of elements, modify theentire list of elements and do not modify the individual elements of thelist.

Hereinafter, with reference to the accompanying drawings, a magnetictunneling junction device and a memory device including the magnetictunneling junction device will be described in detail. Like referencenumerals refer to like elements throughout, and in the drawings, sizesof elements may be exaggerated for clarity and convenience ofexplanation. Various example embodiments described below are merely forillustrative purposes only, and various modifications may be possible.

In a layer structure described below, an expression “above” or “on” mayinclude not only “immediately on in a contact manner” but also “on in anon-contact manner”. An expression used in the singular encompasses theexpression of the plural, unless it has a clearly different meaning inthe context. It will be further understood that the terms “comprises”and/or “comprising” used herein specify the presence of stated featuresor elements, but do not preclude the presence or addition of one or moreother features or elements.

The use of “the” and other demonstratives similar thereto may correspondto both a singular form and a plural form. Unless the order ofoperations of a method according to example embodiments is explicitlymentioned or described otherwise, the operations may be performed in aproper order. Example embodiments are not necessarily limited to theorder the operations are mentioned.

The term used in the embodiments such as “unit” or “module” indicates aunit for processing at least one function or operation, and may beimplemented in hardware or software, or in a combination of hardware andsoftware.

The connecting lines, or connectors shown in the various figurespresented are intended to represent functional relationships and/orphysical or logical couplings between the various elements. It should benoted that many alternative or additional functional relationships,physical connections or logical connections may be present in apractical device.

The use of any and all examples, or language provided herein, isintended merely to better illuminate various example embodiments anddoes not pose a limitation on the scope unless otherwise claimed.

FIG. 1 is a cross-sectional view illustrating a schematic structure of amagnetic tunneling junction device 100 according to some exampleembodiments. Referring to FIG. 1 , the magnetic tunneling junctiondevice 100 according to some example embodiments may include a seedlayer 110 disposed on an electrode 101, a pinned layer 120 disposed onthe seed layer 110, a tunnel barrier layer 130 disposed on the pinnedlayer 120, and a free layer 140 disposed on the tunnel barrier layer130. Although not shown, a capping metal may or may not be furtherdisposed on the free layer 140. Here, the expression “disposed on” isfor convenience of description and does not necessarily mean a verticalrelationship. For example, the seed layer 110 may be disposed to contacta first surface S1 of the pinned layer 120. The free layer 140 may bedisposed to face a second surface S2 opposite to the first surface S1 ofthe pinned layer 120. In addition, the tunnel barrier layer 130 may bedisposed between the pinned layer 120 and the free layer 140.

The electrode 101 may include a conductive material capable of applyinga current to the magnetic tunneling junction device 100. The electrode101 may include a low-resistance metal and/or a metal nitride. Forexample, the electrode 101 may include TiN and/or TaN. The electrode 101may be considered as a part of the magnetic tunneling junction device100 or as a part of a memory device including the magnetic tunnelingjunction device 100.

The pinned layer 120 and the free layer 140 may include a ferromagneticmetal material having magnetism. For example, the pinned layer 120 andthe free layer 140 may include the same or different materials, and mayinclude independently or concurrently at least one ferromagneticmaterial selected from the group consisting of iron (Fe), cobalt (Co),nickel (Ni), manganese (Mn), a Fe-containing alloy, a Co-containingalloy, a Ni-containing alloy, a Mn-containing alloy or a Heusler alloy.The pinned layer 120 may have a pinned magnetization direction, and thefree layer 140 may have a variable magnetization direction. The magnetictunneling junction device 100 may have a relatively low resistance whenthe pinned layer 120 and the free layer 140 have the same, or parallel,magnetization direction, and a relatively high resistance when themagnetization directions are opposite, or antiparallel. This phenomenonis called tunneling magnetoresistance (TMR). The magnetic tunnelingjunction device 100 may be used in a memory device by applying this TMRphenomenon.

The pinned layer 120 and the free layer 140 may have high perpendicularmagnetic anisotropy (PMA), in particular, interface perpendicularmagnetic anisotropy (IPMA). For example, the perpendicular magneticanisotropy energy of the pinned layer 120 and the free layer 140 mayexceed out-of-plane demagnetization energy. In this case, the magneticmoments of the pinned layer 120 and the free layer 140 may be stabilizedin a direction that is perpendicular to a layer direction. The magnetictunneling junction device 100 may be applied to spin transfertorque-magnetic RAM (STT-MRAM) and/or spin-orbit coupling torque (SOT)MRAM.

The free layer 140 may have a low saturation magnetization (Ms) toimprove an operating speed of the memory device using the magnetictunneling junction device 100. Additionally or alternatively, the freelayer 140 may be further doped with or have incorporated therein anon-magnetic metal element so as to reduce the saturation magnetizationMs of the free layer 140. For example, the free layer 140 may be dopedwith at least one non-magnetic metal from among calcium (Ca), scandium(Sc), yttrium (Y), magnesium (Mg), strontium (Sr), barium (Ba),zirconium (Zr), beryllium (Be), titanium (Ti), hafnium (Hf), vanadium(V), zinc (Zn), niobium (Nb), manganese (Mn), aluminum (Al), chromium(Cr), lithium (Li), cadmium (Cd), lead (Pb), indium (In), gallium (Ga),and tantalum (Ta). The non-magnetic metal doped into the free layer 140may have an oxygen affinity higher than that of the ferromagnetic metalmaterial of the free layer 150.

Alternatively or additionally, if necessary or desirable, the free layer140 may have two or more multi-layer structures including a layerincluding only a ferromagnetic metal material and a layer doped with anon-magnetic metal. The material and structure of the free layer 140 mayreduce or prevent diffusion of oxygen or metal elements in an interfacewith the tunnel barrier layer 130 which will be described below.

The tunnel barrier layer 130 may serve to provide a magnetic tunnelingjunction between the pinned layer 120 and the free layer 140. The tunnelbarrier layer 130 may include crystalline metal oxide. For example, thetunnel barrier layer 130 may include one or more of MgO, MgAl₂O₄, orMgTiO_(x).

A crystal direction of a material used as the electrode 101 is mainly a(111) direction. Meanwhile, a crystal of a ferromagnetic metal materialused in the pinned layer 120 disposed on the electrode 101 mainly has ahexagonal close-packed (HCP) structure in which a crystal direction is(0001) or a face centered cubic (FCC) structure. Accordingly, when thepinned layer 120 is directly formed on the electrode 101, the crystaldirection of the electrode 101 and the crystal direction of the pinnedlayer 120 may collide with each other in a heat treatment process ofcrystallizing the pinned layer 120. As a result, a crystal texture ofthe electrode 101 may be partially transferred to the pinned layer 120,and thus a crystal quality of the pinned layer 120 may deteriorate. Theseed layer 110 is disposed between the electrode 101 and the pinnedlayer 120 to prevent or reduce an amount of and/or an impact fromdeterioration of the crystallinity of the pinned layer 120.

The seed layer 110 may include an amorphous material in order to preventor reduce an amount of and/or impact from the crystal structure of theelectrode 101 from being transferred to the pinned layer 120. The seedlayer 110 may also include a material on which a crystal of the HCP orFCC structure can grow. In addition, the seed layer 110 may include amaterial capable of being maintained in an amorphous state without beingdiffused into the pinned layer 120 in a heat treatment process of arelatively high temperature, for example, about 300° C. to about 500°C., or about 400° C. to about 500° C. To this end, the seed layer 110may not include boron (B). When boron is included in the seed layer 110,the boron may diffuse into the pinned layer 120 at a temperature equalto or greater than about 400° C., and thus the crystallinity of thepinned layer 120 may deteriorate. Due to this, a TMR ratio and anexchange field (Hex) of the magnetic tunneling junction device 100 maydeteriorate.

For example, the seed layer 110 may include at least one amorphousmaterial selected from CoFeX and CoFeXTa. For example, the seed layer110 may include a ternary material including Co, Fe, and X, or aquaternary material including Co, Fe, Ta, and X. Here, X may include,for example, at least one element selected from niobium (Nb), molybdenum(Mo), tungsten (W), chromium (Cr), zirconium (Zr), and hafnium (Hf). Aratio of element X in the seed layer 110 may be about 5 at % to about 50at %. In addition, a thickness of the seed layer 110 may be about 5 Å toabout 15 Å.

FIG. 2 is a cross-sectional view illustrating a schematic structure of amagnetic tunneling junction device 100 a according to some exampleembodiments. Referring to FIG. 2 , the seed layer 110 of the magnetictunneling junction device 100 a may include a first seed layer 110 adisposed on the electrode 101 and a second seed layer 110 b disposed onthe first seed layer 110 a. The first seed layer 110 a may be disposedto face the first surface S1 of the pinned layer 120, and the secondseed layer 110 b may be disposed between the first seed layer 110 a andthe pinned layer 120 to be in contact with the first seed layer 110 aand the first surface S1 of the pinned layer 120. According to someexample embodiments, the first seed layer 110 a may include amorphousCoFeX and the second seed layer 110 b may include tantalum (Ta). Inother words, the first seed layer 110 a may include a ternary materialincluding Co, Fe, and X. It may be seen that the first seed layer 110 aand the second seed layer 110 b are disposed on separate layers byseparating CoFeX and Ta from among CoFeXTa which is the material of theseed layer 110 described with reference to FIG. 1 . Meanwhile, the seedlayer 110 of FIG. 1 including CoFeXTa may be a single layer. A thicknessof the second seed layer 110 b may be smaller than a thickness of thefirst seed layer 110 a. For example, the thickness of the second seedlayer 110 b may be about 2 Å to about 5 Å.

Meanwhile, the pinned layer 120 has one of an HCP structure or an FCCstructure, while the tunnel barrier layer 130 and the free layer 140thereon have a body centered cubic (BCC) structure. Accordingly, whenthe tunnel barrier layer 130 and the free layer 140 are directly formedon the pinned layer 120, because different crystal structures collidewith each other, the crystal quality of the tunnel barrier layer 130 andthe free layer 140 may deteriorate. In order to prevent or reduce anamount of and/or impact from deterioration of crystallinity of thetunnel barrier layer 130 and the free layer 140, additional layers maybe further disposed between the pinned layer 120 and the tunnel barrierlayer 130.

FIG. 3 is a cross-sectional view showing a schematic structure of amagnetic tunneling junction device 100 b according to some exampleembodiments. Referring to FIG. 3 , the magnetic tunneling junctiondevice 100 b may further include an anti-crystallized layer 151 disposedbetween the pinned layer 120 and the tunnel barrier layer 130.Alternatively or additionally, the magnetic tunneling junction device100 b may further include a polarization enhancing layer 152 disposedbetween the anti-crystallized layer 151 and the tunnel barrier layer130. In this case, the pinned layer 120, the anti-crystallized layer151, the polarization enhancing layer 152, the tunnel barrier layer 130,and the free layer 140 may be sequentially formed on an upper surface ofthe seed layer 110.

The anti-crystallized layer 151 may prevent or reduce an amount ofand/or impact from a crystal structure of the pinned layer 120 frombeing transferred to the tunnel barrier layer 130 and the free layer140, and may serve to help the pinned layer 120 on a lower portion andthe tunnel barrier layer 130 and the free layer 140 on an upper portionto have their intrinsic crystallinity. For example, theanti-crystallized layer 151 may be referred to as a texture blockinglayer. It may be advantageous that the anti-crystallized layer 151 usesa material that is or is maintained in an amorphous state even duringheat treatment at a relatively high temperature and does not orminimally diffuses into surrounding layers. For example, theanti-crystallized layer 151 may include a material capable of beingmaintained in the amorphous state without diffusing to surroundinglayers in a heat treatment process of a relatively high temperatureabout 300° C. to about 500° C., or about 400° C. to about 500° C. Tothis end, the anti-crystallized layer 151 may include at least one ofYCo, YFe, YCoFe, YCoB, YFeB, or YCoFeB. Here, Y may include, forexample, at least one element selected from tungsten (W), rhenium (Re),molybdenum (Mo), and tantalum (Ta). When the anti-crystallized layer 151includes YFeB, a ratio of FeB in the anti-crystallized layer 151 may beabout 20 at % to about 60 at %, and a ratio of boron (B) in FeB may beabout 10 at % to about 30 at %. A thickness of the anti-crystallizedlayer 151 may be about 1.5 Å to about 10 Å.

The polarization enhancing layer 152 may serve to assist growth of thetunnel barrier layer 130 and the free layer 140 on the anti-crystallizedlayer 151. Alternatively or additionally, the polarization enhancinglayer 152 may have a crystal structure similar to that of the tunnelbarrier layer 130 or the free layer 140, and may further improve thecrystal quality of the tunnel barrier layer 130 and the free layer 140formed on the anti-crystallized layer 151. To this end, the polarizationenhancing layer 152 may include a ferromagnetic material similar to thatof the free layer 140. For example, the polarization enhancing layer 152may include at least one of iron (Fe), cobalt (Co), nickel (Ni),manganese (Mn), an Fe-containing alloy, a Co-containing alloy, aNi-containing alloy, a Mn-containing alloy or a Heusler alloy. Thepolarization enhancing layer 152 may further include boron. For example,the polarization enhancing layer 152 may include CoFeB. A thickness ofthe polarization enhancing layer 152 may be about 5 Å to about 10 Å.

FIG. 4 is a cross-sectional view showing a schematic structure of amagnetic tunneling junction device 100 c according to some exampleembodiments. Referring to FIG. 4 , the pinned layer 120 of the magnetictunneling junction device 100 c may include synthetic antiferromagnet(SAF). The pinned layer 120 may include, for example, a firstferromagnetic layer 120 a in contact with the seed layer 110, a secondferromagnetic layer 120 c in contact with the anti-crystallized layer151, and a SAF coupling layer 120 b disposed between the firstferromagnetic layer 120 a and the second ferromagnetic layer 120 c. Inthis case, the first ferromagnetic layer 120 a, the SAF coupling layer120 b, the second ferromagnetic layer 120 c, the anti-crystallized layer151, the polarization enhancing layer 152, the tunnel barrier layer 130,and the free layer 140 may be sequentially formed on an upper surface ofthe seed layer 110. The SAF coupling layer 120 b may include aconductive metal. For example, the SAF coupling layer 120 b may includeat least one of iridium (Ir), ruthenium (Ru), aluminum (Al), copper(Cu), silver (Ag), or an alloy including the same. Each of the firstferromagnetic layer 120 a and the second ferromagnetic layer 120 c mayindependently or concurrently have a single layer structure including aferromagnetic metal and/or an alloy of a ferromagnetic metal and atransition metal, or may have a multilayer structure including aplurality of layers including a ferromagnetic metal or an alloy of aferromagnetic metal and a transition metal. For example, each of thefirst ferromagnetic layer 120 a and the second ferromagnetic layer 120 cmay include a single layer structure or a multilayer structure includingCo, Fe, CoPt, FePt, CoFe, etc. In such a structure of the pinned layer120, the first ferromagnetic layer 120 a and the second ferromagneticlayer 120 c may form an antiferromagnet by means of the SAF couplinglayer 120 b by the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. Forexample, the pinned layer 120 may have a stable state when amagnetization direction of the first ferromagnetic layer 120 a and amagnetization direction of the second ferromagnetic layer 120 c areopposite to each other. For example, the first ferromagnetic layer 120 amay be magnetized toward a lower surface and the second ferromagneticlayer 120 c may be magnetized toward an upper surface, or the firstferromagnetic layer 120 a may be magnetized toward an upper surface andthe second ferromagnetic layer 120 c may be magnetized toward a lowersurface. The first ferromagnetic layer 120 a and the secondferromagnetic layer 120 c magnetized in opposite directions (orantiparallel with each other) may offset stray magnetic fields from eachother. Therefore, the first ferromagnetic layer 120 a and the secondferromagnetic layer 120 c magnetized in opposite directions to eachother may be used, thereby reducing or preventing the stray magneticfield generated in the pinned layer 120 from affecting the free layer140.

FIG. 5 is a cross-sectional view showing a schematic structure of amagnetic tunneling junction device 100 d according to some exampleembodiments. Referring to FIG. 5 , the polarization enhancing layer 152of the magnetic tunneling junction device 100 d may include a firstpolarization enhancing layer 152 a in contact with the anti-crystallizedlayer 151 and a second polarization enhancing layer 152 b disposedbetween the first polarization enhancing layer 152 a and the tunnelbarrier layer 130. In this case, the first ferromagnetic layer 120 a,the SAF coupling layer 120 b, the second ferromagnetic layer 120 c, theanti-crystallized layer 151, the first polarization enhancing layer 152a, the second polarization enhancing layer 152 b, the tunnel barrierlayer 130, and the free layer 140 may be sequentially formed on an uppersurface of the seed layer 110.

The first polarization enhancing layer 152 a and the second polarizationenhancing layer 152 b may include the same material but may havedifferent composition ratios. The first polarization enhancing layer 152a and the second polarization enhancing layer 152 b may include, forexample, CoFeB. A ratio of boron (B) in the second polarizationenhancing layer 152 b may be less than a ratio of boron (B) in the firstpolarization enhancing layer 152 a. For example, the ratio of boron (B)in the first polarization enhancing layer 152 a may be about 25 at % toabout 35 at %, and the ratio of boron (B) in the second polarizationenhancing layer 152 b may be about 15 at % to about 25 at %.Alternatively or additionally, a thickness of the second polarizationenhancing layer 152 b may be less than a thickness of the firstpolarization enhancing layer 152 a. For example, the thickness of thefirst polarization enhancing layer 152 a may be about 5 Å to about 7 Å,and the thickness of the second polarization enhancing layer 152 b maybe about 1 Å to about 3 Å. A crystal structure may be easily changedfrom the pinned layer 120 to the free layer 140 through a gradual changein the composition ratio in the polarization enhancing layer 152.Accordingly, the crystal quality of the tunnel barrier layer 130 and thefree layer 140 may be further improved.

As described above, a material of the seed layer 110 may be a materialthat is or is maintained in an amorphous state during a heat treatmentprocess of a relatively high temperature, and may not diffuse or maydiffuse relatively little into surrounding layers. In addition, theanti-crystallized layer 151 may also be maintained in an amorphous stateduring a heat treatment process of a relatively high temperature, andmay not diffuse or may diffuse relatively little into surroundinglayers. Therefore, the magnetic tunneling junction device according tosome example embodiments may have a high temperature resistance, andthus a heat treatment may be performed at a relatively high temperaturewhen the magnetic tunneling junction device according to some exampleembodiments is manufactured, and subsequent processes after the heattreatment may also be performed at a relatively high temperature.Accordingly, the crystal quality of magnetic materials in the pinnedlayer 120 and the free layer 140 may be improved. As a result, themagnetic tunneling junction device according to the embodiments may havea relatively high TMR ratio and/or a relatively high exchange field(Hex).

FIG. 6 is a cross-sectional view illustrating a part of a manufacturingprocess of a magnetic tunneling junction device. Referring to FIG. 6 ,the seed layer 110 may be formed on the electrode 101, the pinned layer120 and the anti-crystallized layer 151 may be sequentially formed onthe seed layer 110, and then the pinned layer 120 may be firstcrystallized through a heat treatment process. The seed layer 110 may beformed by depositing the first seed layer 110 a on the electrode 101 anddepositing the second seed layer 110 b on the first seed layer 110 a, asshown in FIG. 2 . The pinned layer 120 may be formed by sequentiallydepositing the first ferromagnetic layer 120 a, the SAF coupling layer120 b, and the second ferromagnetic layer 120 c on the seed layer 110.The heat treatment may be performed through rapid thermal annealing(RTA), for example, from about 300° C. to about 500° C., from about 300°C. to about 450° C., from about 350° C. to about 450° C., or from about450° C. to about 500° C. The RTA may be performed for about 10 secondsto about 200 seconds.

Thereafter, the polarization enhancing layer 152 shown in FIG. 3 may beformed on the anti-crystallized layer 151, and the tunnel barrier layer130 and the free layer 140 may be deposited on the polarizationenhancing layer 152. Alternatively, the polarization enhancing layer 152may be formed by depositing the first polarization enhancing layer 152 aon the anti-crystallized layer 151 and the second polarization enhancinglayer 152 b on the first polarization enhancing layer 152 a, as shown inFIG. 5 . After depositing the free layer 140, the tunnel barrier layer130 and the free layer 140 may be crystallized through a heat treatmentagain. The heat treatment may be performed through an additional RTA,for example, from about 300° C. to about 500° C., from about 300° C. toabout 450° C., from about 350° C. to about 450° C., or from about 450°C. to about 500° C. The additional RTA may be performed for about 100seconds to about 400 seconds. Through this process, the crystal qualityof the pinned layer 120 may be further improved.

FIG. 7 is a graph illustrating results of X-ray diffraction (XRD)analysis of the seed layer 110. FIG. 7 illustrates the XRD analysisresults with respect to CoFeNb before a heat treatment and after theheat treatment at 100° C., 200° C., 300° C., 400° C., and 500° C.Referring to FIG. 7 , it may be seen that an amorphous state of CoFeNbis maintained even after the heat treatment at 500° C.

In addition, based on an atomic force microscopy (AFM) analysis, asurface roughness of the seed layer 110 after the heat treatment wasimproved to 0.093 nm. Accordingly, the seed layer 110 may have thesurface roughness equal to or less than 0.1 nm. A surface roughness of aseed layer according to a comparative example including TaB was 0.104nm.

FIG. 8 is a graph illustrating results of XRD analysis of theanti-crystallized layer 151. FIG. 8 illustrates the XRD analysis resultswith respect to WFeB before a heat treatment and after the heattreatment at 50° C., 200° C., 300° C., 400° C., and 500° C. Referring toFIG. 8 , it may be seen that an amorphous state of WFeB is maintainedeven after the heat treatment at 500° C.

According to an AFM analysis, it was confirmed that the crystallinity ofthe pinned layer 120 may be improved through the heat treatment processshown in FIG. 6 , and thus a surface roughness of the pinned layer 120was slightly improved from 0.138 nm before the heat treatment to 0.135nm after the heat treatment.

FIG. 9 is a graph illustrating a resistance-area product and a TMR ratioof magnetic tunneling junction devices according to variousmanufacturing process conditions. In FIG. 9 , “Ref” represents aresistance-area product and a TMR ratio of a comparative example. Insome example embodiments, CoFeNb was used as a seed layer and WFeB wasused as an anti-crystallized layer. In the comparative example, TaBcontaining boron was used as a seed layer, and only W was used alone asan anti-crystallized layer. In addition, in a structure according tosome example embodiments, a heat treatment was performed for 200 secondsat a temperature of 300° C., 200 seconds at a temperature of 350° C., 30seconds at a temperature of 375° C., 100 seconds at a temperature of375° C., 200 seconds at a temperature of 375° C., 200 seconds at atemperature of 400° C., and 200 seconds at a temperature of 425° C. InFIG. 9 , “MgO 280s” means that MgO is used as a material of the tunnelbarrier layer 130 and is deposited for 280 seconds, and “MgO 290s” meansthat MgO is deposited for 290 seconds. In FIG. 9 , in all examples inwhich “MgO 280s” or “MgO 290s” is not indicated, MgO is deposited for300 seconds. In addition, the resistance-area product and the TMR ratioof each of seven magnetic tunneling junction devices including pinnedlayers having different thicknesses were measured in the comparativeexample and the embodiments. The TMR ratio is a ratio of a lowresistance to a high resistance of the magnetic tunneling junctiondevice, and may be expressed as “(high resistance-low resistance)/lowresistance”. Referring to FIG. 9 , in various example embodiments, ahigh TMR ratio was achieved compared to the comparative example underall heat treatment conditions. For example, in the embodiments, the TMOratio was about 170% to about 190% and was increased as a heat treatmenttemperature increases and a heat treatment time increases. In addition,when a deposition time of MgO is reduced to 280 seconds or 290 seconds,the resistance-area product equal to or less than 8 Ω μm² (Ohms persquare micron) was achieved. For example, when the deposition time ofMgO is reduced to 280 seconds or 290 seconds, an average resistance-areaproduct in each of the embodiments was about 5.4 to about 7.1, and anaverage TMO ratio was about 178% to 184% in each of the embodiments inwhich the deposition time of MgO is reduced to 280 seconds or 290seconds.

FIG. 10 is a graph illustrating a Kerr rotation angle with respect to anexternal magnetic field in a magnetic tunneling junction deviceaccording to some example embodiments compared with a comparativeexample. Referring to FIG. 10 , CoFeNb was used as a seed layer and WFeBwas used as an anti-crystallized layer in some example embodiments. Inthe comparative example, TaB containing boron was used as a seed layer,and only W was used alone as an anti-crystallized layer. In addition, inembodiments, a heat treatment was performed at a temperature of 400° C.,and in the comparative example, the heat treatment was performed at atemperature of 300° C. Referring to FIG. 10 , in the comparativeexample, deterioration of a pinned layer started at about 5000 Oe(Oersted). For example, when intensity of the external magnetic field isequal to or greater than about 5000 Oe, a magnetization direction of afirst ferromagnetic layer and a magnetization direction of the secondferromagnetic layer of the pinned layer are the same as a direction ofthe external magnetic field, and properties of an antiferromagnet arelost. Meanwhile, in embodiments, the pinned layer maintains theproperties of the antiferromagnet up to about 11000 Oe, and when theintensity of the external magnetic field is equal to or greater thanabout 11000 Oe, the magnetization direction of the first ferromagneticlayer and the magnetization direction of the second ferromagnetic layerof the pinned layer are the same. Therefore, it may be confirmed thatthe magnetic tunneling junction device according to example embodimentshas a higher exchange field (Hex) and a higher stability compared withthe comparative example.

FIG. 11 is a cross-sectional view showing a schematic structure of amagnetic tunneling junction device 100 e according to some exampleembodiments. Referring to FIG. 11 , the magnetic tunneling junctiondevice 100 e may further include an oxide layer 160 disposed on the freelayer 140. In some example embodiments, the oxide layer 160 may serve asa capping layer. In this case, the oxide layer 160 usually includes thesame material as that of the tunnel barrier layer 130, but is notnecessarily limited thereto and may include any oxide material.Meanwhile, in some example embodiments, the oxide layer 160 may includean oxide material that directly contacts an upper surface of the freelayer 140 and has absorptivity to boron in order to absorb boron in thefree layer 140. For example, the oxide layer 160 may include at leastone oxide material selected from the group consisting of or includingHfOx, NbOx, TaOx, and WOx. The oxide layer 160 may absorb boron in thefree layer 140, and thus a concentration of boron in the free layer 140may be reduced. Then, a saturation magnetization of the free layer 140may be reduced, and thus an operation speed of the magnetic tunnelingjunction device 100 e may be improved.

FIG. 12 schematically illustrates one memory cell including the magnetictunneling junction device 100 according to some example embodiments.Referring to FIG. 12 , the memory cell MC may include theabove-described magnetic tunneling junction device 100 and a switchingdevice TR connected to the magnetic tunneling junction device 100. Theswitching device TR may be or may include a transistor such as a thinfilm transistor. The memory cell MC may be connected between a bit lineBL and a word line WL. The bit line BL and the word line WL may bedisposed to cross each other (e.g. to be perpendicular to each other),and the memory cell MC may be disposed in or at an intersection point ofthe bit line BL and the word line WL. The bit line BL may beelectrically connected to the free layer 140 of the magnetic tunnelingjunction device 100 and the word line WL may be connected to a gate ofthe switching device TR. In addition, a first source/drain electrode ofthe switching device TR may be electrically connected to the electrode101 of the magnetic tunneling junction device 100 and a secondsource/drain electrode of the switching device TR may be electricallyconnected to a selection line SL. The selection line SL may extendparallel with the word line. In this structure, one or more of a writecurrent, a read current, an erase current, etc. may be applied to thememory cell MC through the word line WL and the bit line BL. In FIG. 12, it is shown that the memory cell MC includes the magnetic tunnelingjunction device 100 shown in FIG. 1 , but in some example embodiments,the memory cell MC may include a magnetic tunneling junction device ofother example embodiments.

FIG. 13 is a circuit diagram schematically illustrating a configurationof a memory device 600 including the plurality of memory cells MCs shownin FIG. 12 . Referring to FIG. 13 , the memory device 600 may include aplurality of bit lines BL, a plurality of word lines WL, a plurality ofselection lines SL, the plurality of memory cells MCs respectivelydisposed in intersection points of the plurality of bit lines BL and theplurality of word lines WL, a bit line driver 601 applying current tothe plurality of bit lines BL, a word line driver 602 applying currentto the plurality of word lines WL and a selection line driver 603applying current to the plurality of selection lines SL. Each memorycell MC may have the configuration shown in FIG. 12 . The memory device600 may be a “1T1MTJ” device, e.g. a one transistor, one magnetictunneling junction device.

The memory device 600 illustrated in FIG. 13 may be or may include amagnetic random access memory (MRAM), and may be used in electronicdevices using nonvolatile memory. In particular, the memory device 600illustrated in FIG. 13 may be or may include an STT-MRAM in which amagnetization direction of a free layer is changed by a spin currentdirectly applied to the free layer of the magnetic tunneling junctiondevice. The STT-MRAM does not require or use a separate wire forgenerating an external magnetic field, and thus the STT-MRAM may beadvantageous for high integration and has a simple operation method. Inaddition, the memory device 600 shown in FIG. 13 may also be applied toSOT-MRAM.

FIG. 14 is a block diagram of an electronic apparatus 700 according tosome example embodiments. Referring to FIG. 14 , an electronic apparatus700 may constitute a wireless communication device, or a device capableof transmitting and/or receiving information in a wireless environment.The electronic apparatus 700 includes a controller 710, an input/output(I/O) device 720, a memory 730, and a wireless interface 740, which areinterconnected through a bus 750.

The controller 710 may include at least one of a microprocessor, adigital signal processor, or a processing apparatus similar thereto. TheI/O device 720 may include at least one of a keypad, a keyboard, and adisplay. The memory 730 may be used to store commands executed bycontroller 710. For example, the memory 730 may be used to store userdata.

In some example embodiments, the memory 730 may include a magnetictunneling junction device such as one or more of the magnetic tunnelingjunction devices 100 described above.

The electronic apparatus 700 may use the wireless interface 740 totransmit/receive data through a wireless communication network. Thewireless interface 740 may include an antenna and/or a wirelesstransceiver. In some embodiments, the electronic apparatus 700 may beused for a communication interface protocol of a third generationcommunication system, for example, one or more of a code divisionmultiple access (CDMA), a global system for mobile communications (GSM),a north American digital cellular (NADC), an extended-time divisionmultiple access (E-TDMA), and/or a wide band code division multipleaccess (WCDMA).

When the terms “about” or “substantially” are used in this specificationin connection with a numerical value, it is intended that the associatednumerical value includes a manufacturing or operational tolerance (e.g.,±10%) around the stated numerical value. Moreover, when the words“generally” and “substantially” are used in connection with geometricshapes, it is intended that precision of the geometric shape is notrequired but that latitude for the shape is within the scope of exampleembodiments. Moreover, when the words “generally” and “substantially”are used in connection with material composition, it is intended thatexactitude of the material is not required but that latitude for thematerial is within the scope of various example embodiments.

Further, regardless of whether numerical values or shapes are modifiedas “about” or “substantially,” it will be understood that these valuesand shapes should be construed as including a manufacturing oroperational tolerance (e.g., ±10%) around the stated numerical values orshapes. Thus, while the term “same,” “identical,” or “equal” is used indescription of example embodiments, it should be understood that someimprecisions may exist. Thus, when one element or one numerical value isreferred to as being the same as another element or equal to anothernumerical value, it should be understood that an element or a numericalvalue is the same as another element or another numerical value within adesired manufacturing or operational tolerance range (e.g., ±10%).

Although the magnetic tunneling junction device and the memory deviceincluding the magnetic tunneling junction device are described withreference to the drawings, it should be understood that embodimentsdescribed herein should be considered in a descriptive sense only andnot for purposes of limitation. Descriptions of features and/or aspectswithin each embodiment should typically be considered as available forother similar features and/or aspects in other embodiments. While one ormore embodiments have been described with reference to the figures, itwill be understood by those of ordinary skill in the art that variouschanges in form and details may be made therein without departing fromthe spirit and scope as defined by the following claims.

It should be understood that embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments. While one or more embodiments have beendescribed with reference to the figures, it will be understood by thoseof ordinary skill in the art that various changes in form and detailsmay be made therein without departing from the spirit and scope asdefined by the following claims.

What is claimed is:
 1. A magnetic tunneling junction device comprising:a pinned layer having a first surface and a second surface opposite thefirst surface; a seed layer contacting the first surface of the pinnedlayer; a free layer facing the second surface of the pinned layer; and atunnel barrier layer between the pinned layer and the free layer,wherein the seed layer comprises at least one amorphous materialselected from CoFeX and CoFeXTa, and the X comprises at least oneelement selected from niobium (Nb), molybdenum (Mo), tungsten (W),chromium (Cr), zirconium (Zr), and hafnium (Hf).
 2. The magnetictunneling junction device of claim 1, wherein a proportion of the X inthe seed layer is 5 at % to 50 at %.
 3. The magnetic tunneling junctiondevice of claim 1, wherein a thickness of the seed layer is 5 Å to 15 Å.4. The magnetic tunneling junction device of claim 1, wherein the seedlayer is a single layer comprising CoFeXTa.
 5. The magnetic tunnelingjunction device of claim 1, wherein the seed layer comprises: a firstseed layer facing the first surface of the pinned layer; and a secondseed layer between the pinned layer and the first seed layer to contactthe first surface of the pinned layer.
 6. The magnetic tunnelingjunction device of claim 5, wherein the first seed layer comprises CoFeXand the second seed layer comprises tantalum (Ta).
 7. The magnetictunneling junction device of claim 5, wherein a thickness of the secondseed layer is less than a thickness of the first seed layer.
 8. Themagnetic tunneling junction device of claim 1, further comprising: ananti-crystallized layer between the pinned layer and the tunnel barrierlayer; and a polarization enhancing layer between the anti-crystallizedlayer and the tunnel barrier layer.
 9. The magnetic tunneling junctiondevice of claim 8, wherein the seed layer and the anti-crystallizedlayer are in an amorphous state at a temperature of 300° C. to 500° C.10. The magnetic tunneling junction device of claim 8, wherein theanti-crystallized layer comprises at least one of YCo, YFe, YCoFe, YCoB,YFeB, or YCoFeB, and the Y comprises at least one element selected fromtungsten (W), rhenium (Re), molybdenum (Mo), and tantalum (Ta).
 11. Themagnetic tunneling junction device of claim 10, wherein theanti-crystallized layer comprises YFeB, a proportion of FeB in theanti-crystallized layer is 20 at % to 60 at %, and a proportion of boron(B) in the FeB is 10 at % to 30 at %.
 12. The magnetic tunnelingjunction device of claim 10, wherein a thickness of theanti-crystallized layer is 1.5 Å to 10 Å.
 13. The magnetic tunnelingjunction device of claim 8, wherein the polarization enhancing layercomprises CoFeB.
 14. The magnetic tunneling junction device of claim 8,wherein the polarization enhancing layer comprises: a first polarizationenhancing layer in contact with the anti-crystallized layer; and asecond polarization enhancing layer between the first polarizationenhancing layer and the tunnel barrier layer.
 15. The magnetic tunnelingjunction device of claim 14, wherein each of the first polarizationenhancing layer and the second polarization enhancing layer comprisesCoFeB, and a proportion of boron (B) in the second polarizationenhancing layer is less than a proportion of boron (B) in the firstpolarization enhancing layer.
 16. The magnetic tunneling junction deviceof claim 15, wherein the proportion of boron (B) in the firstpolarization enhancing layer is 25 at % to 35 at %, and the proportionof boron (B) in the second polarization enhancing layer is 15 at % to 25at %.
 17. The magnetic tunneling junction device of claim 15, wherein athickness of the second polarization enhancing layer is less than athickness of the first polarization enhancing layer.
 18. The magnetictunneling junction device of claim 17, wherein the thickness of thefirst polarization enhancing layer is 5 Å to 7 Å, and the thickness ofthe second polarization enhancing layer is 1 Å to 3 Å.
 19. The magnetictunneling junction device of claim 18, wherein the pinned layercomprises a first ferromagnetic layer in contact with the seed layer, asecond ferromagnetic layer in contact with the anti-crystallized layer,and a synthetic antiferromagnet (SAF) coupling layer between the firstferromagnetic layer and the second ferromagnetic layer, and amagnetization direction of the first ferromagnetic layer and amagnetization direction of the second ferromagnetic layer are oppositeto each other.
 20. The magnetic tunneling junction device of claim 1,further comprising: an oxide layer on the free layer.
 21. A method ofmanufacturing a magnetic tunnel junction device, the method comprising:forming a seed layer on an electrode; forming a pinned layer on the seedlayer; forming an anti-crystallized layer on the pinned layer;performing heat treatment for crystallizing the pinned layer; forming apolarization enhancing layer on the anti-crystallized layer; forming atunnel barrier layer on the polarization enhancing layer; and forming afree layer on the tunnel barrier layer, wherein the seed layer comprisesat least one amorphous material selected from CoFeX and CoFeXTa, and theX comprises at least one element selected from niobium (Nb), molybdenum(Mo), tungsten (W), chromium (Cr), zirconium (Zr), and hafnium (Hf). 22.The method of claim 21, wherein the heat treatment is performed at atemperature of 300° C. to 500° C.
 23. The method of claim 21, wherein aproportion of the X in the seed layer is 5 at % to 50 at %.
 24. Themethod of claim 21, wherein a thickness of the seed layer is 5 Å to 15Å.
 25. The method of claim 21, wherein the seed layer is a single layercomprising CoFeXTa.
 26. The method of claim 21, wherein the forming ofthe seed layer comprises, forming a first seed layer comprising CoFeX,on an electrode; and forming a second seed layer comprising tantalum(Ta), on the first seed layer.
 27. The method of claim 21, wherein theanti-crystallized layer comprises at least one of YCo, YFe, YCoFe, YCoB,YFeB, or YCoFeB, and the Y comprises at least one element selected fromtungsten (W), rhenium (Re), molybdenum (Mo), and tantalum (Ta).
 28. Themethod of claim 27, wherein the anti-crystallized layer comprises YFeB,a proportion of FeB in the anti-crystallized layer is 20 at % to 60 at%, and a proportion of boron (B) in the FeB is 10 at % to 30 at %. 29.The method of claim 27, wherein a thickness of the anti-crystallizedlayer is 1.5 Å to 10 Å.
 30. The method of claim 21, wherein the seedlayer and the anti-crystallized layer are in an amorphous state at atemperature of 300° C. to 500° C.
 31. The method of claim 21, whereinthe forming of the polarization enhancing layer comprises forming afirst polarization enhancing layer on the anti-crystallized layer; andforming a second polarization enhancing layer on the first polarizationenhancing layer, and each of the first polarization enhancing layer andthe second polarization enhancing layer comprises CoFeB, and aproportion of boron (B) in the second polarization enhancing layer issmaller than a proportion of boron (B) in the first polarizationenhancing layer.
 32. The method of claim 31, wherein the proportion ofboron (B) in the first polarization enhancing layer is 25 at % to 35 at%, and the proportion of boron (B) in the second polarization enhancinglayer is 15 at % to 25 at %.
 33. A memory device comprising: a pluralityof magnetic tunneling junction devices; and a plurality of switchingdevices, each of the plurality of switching devices being connected to arespective one of plurality of magnetic tunneling junction devices,wherein the respective one of the plurality of magnetic tunnelingjunction devices comprises: a pinned layer having a first surface and asecond surface opposite the first surface; a seed layer contacting withthe first surface of the pinned layer; a free layer facing the secondsurface of the pinned layer; and a tunnel barrier layer between thepinned layer and the free layer, wherein the seed layer comprises atleast one amorphous material selected from CoFeX and CoFeXTa, and the Xcomprises at least one element selected from niobium (Nb), molybdenum(Mo), tungsten (W), chromium (Cr), zirconium (Zr), and hafnium (Hf).